How to calculate PF Impending doom dps

Hi, I am trying to calculate my builds dps in PoB but not sure how, I think I will need to add a custom modifier in the config but cannot find any info on what to add.

The build feels very good as can do any map/uber easily but not sure where to go from here as cannot get reliable info from PoB and it has pretty much been after changing something I would need to play a bit to see if it feels better or worse to play etc.

My build: https://poe.ninja/pob/o2H